Diaphragm pump with flow promoting inlet



May 14, 1968 D. TOSCHKOFF ET AL 3,382,810

DIAPHRAGM PUMP WITH FLOW PROMOTING INLET Filed sept. 1, 1965 United States Patent O 3,382,810 DIAPHRAGM PUMP WITH FLOW PROMOTING INLET Dimitar Toschkotf and Norman J. Raatz, Flint, and

Robert G. Taylor, Flushing, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Sept. 1, 1965, Ser. No. 484,195 1 Claim. (Cl. 103-150) ABSTRACT OF THE DISCLOSURE A fuel pump of the automotive diaphragm type having a pump head with a fixed bafiie arranged transverse to a general path for incoming fluid giving a time-delay action for enhancing pump performance.

This invention relates to pumps and more ,particularly t-o diaphragm pumps specially but not necessarily adapted for handling fuel for internal combustion engines.

Diaphragm pumps are often operated by positive cam action during suction strokes and by spring action during discharge strokes. Attempts have been made to smooth out the discharge flow despite the reciprocative actioni.e., to avoid hydraulic knock and to increase the flow available. One such attempt, merely by way of example and which has been reasonably successful, is disclosed in the United States Patent 2,868,135 granted Jan. 13, 1959, in the name of D. R. Reinertson. That patent discloses dead air spaces separated from inlet and outlet chambers by a so-called pulsator diaphragm. This tends to dampen the liow pulsations and results in a smoother operating pump.

It has become desirable further to increase the smoothness in flow and also the pump capacity while retaining constant such factors as size of pumping chamber, reciprocations per minute of the pumping diaphragm and the general one-way valve arrangement necessary in effecting operation.

An object of the present invention is to provide an improved diaphragm pump in which pulsations of the inlet flow pressure as induced by pump suction are reduced to increase pump capacity. Another object is to provide a low-cost diaphragm pump in which pressure pulsations or surges are largely eliminated on both the inlet and outlet sides of the pump and without the use of an added diaphragm or dead air space.

A feature of the present invention is a diaphragm pump with an inlet valve and a defiector or distributing plate interposed between an inlet and the valve and also a surge chamber surrounding the inlet so that flow defiected from the inlet is delayed in the surge chamber before being directed to the valve. Another feature is a diaphragm pump having a one-way inlet valve and a one-way outlet valve with two covers so joined as to form a deflector and a surge chamber for directing the flow to the inlet valve and a large outlet chamber surrounding both valves for directing the tiow from the outlet valve.-

FIGURE 1 is an elevation view of a fuel pump with portions broken away better to illustrate one embodiment of the present invention; and

FIGURES 2, 3, and 4 are sectional views showing three other embodiments of the invention as related to the inlet side of a pump.

In FIGURE 1, a pump body 1t) is shown as having an operating arm 12 to be operated by some part of an engine such as a reciprocating plunger 14. The body 10 has a flange I6 by which the pump is attached to the side of the engine and also a pumping diaphragm 18 to be reciprocated to effect a pumping action through a pumping chamber 20. These parts are much like the equivalent parts shown in the United States Patent 3,125,218 granted June 2, 1964, to D. Toschkoff. Parts beneath the body 10 as shown in the drawings present a novel arrangement in which the present invention is used.

The bottom of the pump body 10 bears a flange 22 which surrounds a body opening 24 and two covers 26 and 28 are utilized tightly to hold the periphery of the diaphragm 18 to the flange 22. The holding is performed by clinching a flange 30 of the cover v28 tightly around the body flange 22.

Both covers 26 and 28 are of sheet metal and the cover 26, being the inner cover, is so made as to support the inlet valve 32 and the outlet valve 34. These valve are of similar design and each embodies a rivet-like defiector element 36 for restraining the valve with the aid of a compression spring 38 so that each valve tends to be seated. Only ports 40 for the inlet valve are illustrated. These ports are made in a cup element 42 retained within a deeper cup portion 44 formed integral with the inner cover 26. The tubular or cup portion 44 is so made as to provide a fiat baffle 46 surrounded by a series of ports 48.

The outer cover 28 is so formed as to nest with the cup portion 44 of the inner cover in defining a space 50 for a sealing washer 52 and also to cooperate with the baiiie 46 in defining an annular surge chamber 54. An inlet fitting S5 is fixed to the outer cover 28 and an inlet passage 58 of the fitting is directed upward to terminate close to the baffle 46 and is surrounded by a ange 60 extending into the surge chamber 54.

The outer cover 28 partially defines a large outlet chamber 62 and it will be noted that this chamber not only encloses the outlet valve 34 but also surrounds the protruding cylindrical cup portion 44 of the inner cover 26. An outlet fitting 66 is attached to the outer cover 28.

Diaphragm pumps are run continuously while in operation and having a variable displacement, a hydraulic knock is encountered particularly with automotive fuel pumps upon starting engines on a cold day. At high carburetor fuel demand, the fuel flow in the pump suction line is rapidly stopped and started as the fuel pump inlet valve opens and closes. This velocity change at the pump inlet creates cavitation and noise in pump operation.

With the instant pump, the inlet flow direction is changed by the batiie 46 in such a way as to effect a time delay in the flow during-a portion of each pump cycle to effect a steadiness in flow which adds fuel volume. Also, the outlet flow is steadied by the large receiving chamber 62.

In the operation of the fuel pump of FIGURE l, inlet flow passes through the fitting 56 and after being defiected by the flat portion 46 is forced outwardly or radially into the surge chamber 54 wherein a time delay occurs in the fiow but the result is a steady fiow through the ports 48 to the ports 40 of the inlet valve 32. Flow is then through the pumping chamber 20 and out of the pump by way of the outlet valve 34 and the tting 66.

In the modification of FIGURE 2, we again have an outer cover 28 with inlet 32 and an inlet fitting 56 but in this case an inner cover 70 is varied in that a defiector or bathe portion 72, instead of being flat as in the ease of FIGURE l, is made with conical surfaces on opposite sides and converging toward the valve 32 and coaxial with the inlet pasage 58 as well as the valve 32. Here again the surge chamber 54 creates a time delay which is a factor in improving the pump performance.

In the modification of FIGURE 3, the outer cover 28 and fitting 56 with its passage 58 are again empoyed but in this case a baie plate 74 is utilized which is arcuate in part-it is concave on the surface facing the valve 32 and convex on the surface facing the passage 58. The

surge chamber 54 in this version also serves to create a time delay in ow.

FIGURE 4 shows an inner cover 90 which varies from the other inner covers by utilizing a batiie 92 having a convex surface facing the valve 32 and a concave surface facing the inlet passage 58. The surge chamber 54 here again provides the requisite time delay to give the new result.

In numerous tests conducted with each of the abovedescribed versions it has been indicated that the modiiication of FIGURE 2 functions best when the pump is installed with the sheet metal cover 28 directed upwardly. As for the other modifications, however, the time delay function is `best performed by installing the pumps with the sheet metal covers directed downwardly. The reason for this variation is not understood and in fact the reasons why the time delay and increased iiow occurs in using the peculiar baille construction of each Version are not fully understood particularly when it be appreciated that liquid fuel is substantially uncompressible. It would appear, however, that an action occurs somewhat analogous to that of cavitation experienced with marine screw propellers.

We claim:

1. A diaphragm type pump having a supporting body closed by a reciprocable pumping diaphragm, an inner cover bearing an outlet valve, said inner cover having a cup portion formed integral therewith and enclosing an inlet valve, said cup portion having an integral lower wall defining a batiie with at least one port therein, an outer cover deiining an outlet chamber and holding said inner cover in position as well as enclosing said outlet valve and said cup portion, an outlet in said outer cover and spaced from the axis of said inlet valve, said outer cover having a portion spaced from but in axial alignment with said batiie to define therewith a surge chamber, sealing means contacting and surrounding said cup portion and separating said surge chamber from said outlet chamber, an inlet in said outer cover leading to said surge chamber, and an imperforate area of said baffle being fixed in position and traversing a direct path between said outer cover inlet and said inlet valve.

References Cited UNITED STATES PATENTS 2,474,555 6/1949 Stephens 230-236 2,969,745 l/l96l Johnson et al. 13G-150 3,198,128 8/1965 Smith 103-150 3,278,032 1l/l966 Smith 103-150 3,304,880 2/l967 Gold et al. 103-150 DONLEY J. STOCKING, Primary Examiner.

W. L. FREEH, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE 0E CORRECTION Patent No. 3,382,810 May 14, 1968 Dmtar Toschkoff et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Columl Z, line 1, "3,125,218" should read 3,l35,218 line I3, "These valve" should read These valves Signed and sealed this 4th day of November 1969.

SEAL) lttest:

:award M.F1emher,1r. WILLIAM E. SCHUYLER, JR-

Lttesting Officer Commissioner of Patents 

